Transpower says building a back-up power line in the Far North isn't as simple as people might think.
Three of its pylons were shot last month, taking the region off the grid for more than 12 hours.
A Northland business leader is calling for a back-up power line to be installed, however Transpower spokesperson Stephen Jay questions its cost-effectiveness.
"Is it economically viable to spend that money on a major grid investment?" he asks.
"Major grid costs a lot of money to build and then New Zealanders need to pay for that."
Mr Jay says two circuits go into the region and all the insulators were shot at. To have these all go down in succession is an uncommon occurrence.
"It's very, very rare to lose insulators. And to lose a whole stack of insulators on multiple transmission towers is a very very, very rare event."
Two Moerewa men have been charged for allegedly shooting the pylons.